Control systems or industrial controllers are used for controlling industrial processes such as machines, manufacturing equipment, and other factory automation apparatus. An industrial controller receives various process variables or other inputs representative of the status of a controlled process, and generates outputs according to a control program or routine to control the process to one or more desired setpoints, where the inputs and outputs can be binary, (e.g., on or off), and/or analog assuming a continuous range of values. The control system, moreover, can be distributed with two or more modules performing various functions, such as I/O modules interfacing with field devices for sending and receiving outputs and inputs, control modules that run the control program and communicate with I/O modules, etc. In such a distributed control system (DCS), input signals received from the controlled process and the outputs transmitted to the process can pass through one or more input/output (I/O) modules, which serve as an electrical interface between the controller and the controlled process, and can be located proximate or remote from the controller. The modules of a DCS can be spatially distributed along a common communication link in several racks, whereby certain I/O modules can be located close to the controlled process proximate a portion of the control equipment, and remote from the remainder of the control system. Data is typically communicated between modules over a common communication link, or network using a communications protocol.
One problem in conventional control systems is physical interconnection of the field signals of the controlled process with the I/O modules of the control system. For many industrial control applications, such as control of machines or processes involving large numbers of input and output signals, the control system I/O signal terminals must be connected by wires to a number of different sensors, actuators, machines, etc. FIG. 1 illustrates a conventional industrial system 2 having a number of machines 10 constituting a controlled process 14 that send or receive various field signals 12, including outputs and/or inputs, where the field signals 12 may be analog and/or digital signals. The controlled process 14 is operated by a control system 20 that includes control processing elements (not shown) as well as I/O components 22 for coupling analog and/or digital I/O signals 24 associated with the controlled process 14. Wiring terminals 30 are provided as an intermediate connection point for connecting particular field signals 12 and I/O signals 24 with one another such that the control system 20 receives the necessary inputs to ascertain the pertinent operating conditions associated with the controlled process 14 and such that the controlled process 14 receives the necessary output control signals from the control system 20 for controlling the process 14 according to a control program or routine. In the illustrated system 2, wiring terminals 30 provide a location from which the wiring for the field and/or I/O signals 12, 24 may be grouped as needed into cables or the like to facilitate orderly signal interconnection. However, this conventional interconnection approach requires manual connection of each signal wire 12, 24 to the correct terminal 30. Moreover, this interconnection system is difficult to troubleshoot or reconfigure, and the terminal connections must be carefully documented.
In order to simplify control system interconnection, the wiring terminals 30 may be replaced by custom circuit boards having a series of cable connectors with fixed traces routed on the board to provide a specific set of interconnections between I/O cabling and field signal cabling. However, reconfiguration of the system signal interconnections in such an approach requires layout of a new printed circuit board. In this regard, if a component of a controlled process is upgraded, the wiring interconnection requirements may change, and a new custom printed circuit board would be needed. Thus, the conventional control system wiring techniques are customized for a given control application, and are not well suited to troubleshooting or reconfiguration. Furthermore, the wiring terminals 30 and customized printed circuit boards add cost and complexity to the overall industrial system 2, whereby there is a need for improved routing apparatus for interconnecting field wiring from a controlled process with I/O wiring of a control system.